A redundant array of independent disks (RAID), also referred to as a redundant array of inexpensive disks (RAID), is referred to as a disk array for short. A principle of the RAID is to combine a plurality of relatively inexpensive hard disks to form a hard disk array group, so as to provide performance that reaches or even exceeds performance of a pricey hard disk with a huge capacity, and improve data security in combination with a design of distributed data arrangement. According to a different version that is selected, compared with a single hard disk, the RAID can increase a storage capacity, and can also improve data integration and a data error tolerance capability. In addition, for a computer, a disk array looks like an independent hard disk or a logical storage unit.
In an archiving scenario, a large number of files need to be archived. Therefore, in the prior art, a RAID is generally used to store archived files. In addition, to improve data security, a RAID with a check function, for example, in a form of a RAID 3, a RAID 4, a RAID 5, or a RAID 6, is generally used to store archived files. In the prior art, to improve a data access speed, a file is generally divided into several data blocks. A stripe, which includes a plurality of data blocks belonging to one file and check data, is written into a plurality of disks that form the RAID. Because archived files are less frequently accessed, in order to achieve a purpose of energy-saving, disks in a storage system are generally in a sleeping or power-off state after files are archived. When a certain archived file needs to be accessed, the plurality of disks in which data blocks of the file are stored need to be waken up or powered on, so as to read the file.